BLM idea to integrate and encourage usage of both Fire and Ice spells

It's a little odd for BLM's job flavor that they're able to cast only ice/fire spells the entire time instead of switching between them. Instead of trying to balance the "stances", I think it would be more interesting and flavorful if BLM in PvP was brought more in line with the PvE kit (or the old pre-6.1 kit) where BLM has an ice phase and a fire phase. Here's how it could look.

An additional effect added to Superflare:

Enemies under the effect of Umbral Freeze are afflicted with Ice Immunity.
Ice Immunity: prevents accumulation of Umbral Freeze stacks for 10 seconds.

Enemies under the effect of Astral Warmth are afflicted with Fire Immunity.
Fire Immunity: prevents accumulation of Astral Warmth stacks for 10 seconds.

Also, the damage of the main GCD spells should be adjusted so fire emphasizes damage and ice emphasizes control.

Fire: 6000
Fire IV: 8000
Flare: 12000 (8000)

Blizzard: 4000
Blizzard IV: 6000
Freeze: 8000 (6000)

Thoughts? It could raise the skill cap on BLM by adding a dimension of having to manage immunities and timing when you want to be using Ice spells vs. Fire spells. For example, you may want to use Fire when harassing the enemy, but Ice in a teamfight where your teammates can take advantage of the stuns.

Fire-Ice spell potencies can be lowered since it is not the problem regarding Warmth-Freeze. Still, they should have the same potencies as Superflare mechanic is already there to emphasize both of them. No need to do it further, and no need for 6k.

Free 10s immunity to people who got hit by Superflare is not a good idea.
It basically "forces" BLM to use a much less viable option or waste 10s in a team fight. It is a very artificial and forceful way to increase Fire usage while not solving the issue.

The real problem is always the fact that Astral Warmth is usually a waste of a precious and limited resource, not the spell potencies.
Right now, its "harassing" vs "cooler harassing". With only two Superflares, the choice is very clear. If the opposing team has any group regen, BLM can just throw Fire out the window as it basically has no effect.

"Damage" vs "Harassing" is the way to go, and that can be done by simply changing Astral Warmth to a much more immediate or much better result.

To be a bit more interesting and a little bit evil; 4k Burn, refresh duration when hit by Astral Warmth Superflare, and Burn can stack. This also reduces the usage of Ice by the choice of committing to pure Burn damage that is actually a threat. This way, BLM isn't forced to switch between Fire-Ice, but given a choice to commit to one element. The polar opposite of RDM design.